Galactaric acid, preparation

J. F. Fauvarque, G. Guerin, S. Petit etal., Process and electrolytic cell for preparing galactaric acid, Fr. Demande, Fr 2699937, 1994. 

This pyrrole was prepared (Stoll et al., 1967) by reaction of 2-methylbutylamine on mucic (galactaric) acid according to a procedure described by Reichstein (1927). 

Bis(thiocarbonyl)hydrazide derivatives of galactaric acid (186,187) have been prepared by reaction of 2,3,4,5-tetra-Oacetyl-D-galactaroyl dichloride (185) with 4-arylthiosemicarbazides335 or S-methyl(benzyl) hy-drazinecarbodithioates336 (Scheme 56). The adducts were subsequently converted into a variety of bis(heterocyclic) compounds including thiadia-zole, triazole, and oxadiazole derivatives. The tetraacetates 186 have been... 

Tetra-O-methyl-D-mannaric and galactaric acids and their bis(pentachlorophenyl) esters have been prepared [99] as crystalline compounds, in good yields, from D-mannitol and galactitol, respectively. A new stereoregular fully sugar-based polyamide, analogous to Nylon 66, has also been prepared [99] by polycondensation of bis(pentachlorophenyl) 2,3,4,5-tetra-O-methyl-D-mannarate with l,6-diamino-l,6-dideoxy-2,3,4,5-tetra-<9-methyl-D-mannitol dihydrochloride [100]. 

The formation of D-glucaric acid by platinum-catalysed oxidation of D-gluconic acid has been noted in the previous section. Mono- and per-allyl ether derivatives of xylaric and galactaric acids have been prepared by treating the aldaric acid with allyl alcohol in the presence of an appropriate acid catalyst. Diallyl 3-0-allyl-2,4-0-methylenexylarate was obtained in good yield when 2,4-0-methylenexylaric acid reacted with allyl bromide in the presence of alkali. The reaction of 2,3,4-tri-O-acetylxylaryl dichloride with diazomethane has been mentioned in Chapter 7. 

In contrast to galactaric acid, D-mannaric and D-glucaric acids are appreciably soluble in water. Glucaric acid is best prepared by the nitric acid oxidation of starch yields as high as 65% are obtained in contrast to much lower yields from glucose or sucrose 50), This acid is generally characterized as the potassium acid salt or silver salt. 

Pyrrole was first isolated from bone oil it also occurs in coal tar and can be prepared by the dry distillation of the ammonium salt of D-galactaric acid (mucic acid see p. 78). Pyrrole is a colorless Hquid with a characteristic odor reminiscent of chloroform, of mp 24 °C and bp 131 °C. It is slightly soluble in water and turns brown quickly in air. 

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